Oromandibular dystonia--functional and clinical characteristics: a report on 21 cases

Vol. 115 No. 1 January 2013

Oromandibular dystonia—functional and clinical characteristics: a report on 21 cases Merete Bakke, DDS, PhD, Dr.oDont.,a Bo Madvig Larsen, BSc,b Torben Dalager, MD,c and Eigild Møller, DDS, Dr.oDont.,d Copenhagen, Denmark UNIVERSITY OF COPENHAGEN AND BISPEBJERG HOSPITAL

Objectives. The objectives of this study were to describe subtypes, characteristics, and orofacial function of patients with oromandibular dystonia and report results of special dental importance. Study Design. Symptoms, signs, and function were evaluated by questionnaires, video, and clinical and physiological examinations in 21 patients with primary and secondary dystonia (13 focal, 7 segmental, 1 multifocal). Results. A mixture of 2 or more subtypes of jaw movements was most common (43%), and the dystonic electromyographic activity was frequent in the anterior digastric (62%) and temporal and lateral pterygoid (48%) muscles. The impact from the oromandibular dystonia was marked. The prevalence of problems with mastication and swallowing was high, as well as with hyposalivation, dental attrition, and other dental problems. Conclusions. Patients with oromandibular dystonia may present to dentists with involuntary jaw movements and other severe functional problems. Care must be adapted to the neurological disorder and may be complicated by the condition itself. (Oral Surg Oral Med Oral Pathol Oral Radiol 2013;115:e21-e26)

Oromandibular dystonia (OMD) is a rare focal neurological disorder affecting the lower part of the face and jaws. The dystonic activity may look similar to idiopathic sleep bruxism but usually ceases during sleep. It is characterized by sustained or repetitive involuntary jaw and tongue movements and facial grimacing caused by involuntary spasms of the masticatory, facial, pharyngeal, lingual, and lip muscles.1–3 OMD is typically classified as jaw opening, jaw closing, jaw deviating, or lingual dystonia or combinations of these.2,4,5 The combination of OMD, blepharospasms, and dystonic movements of the upper face is known as Meige’s syndrome.6 Oral function has been reported to be compromised in most cases of OMD. Such dysfunction may lead to social embarrassment, reduced quality of life, depression, and weight loss.7–13 OMD often interferes with normal orofacial function, such as chewing and control a

Associate Professor, Department of Oral Medicine (Clinical Oral Physiology), School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. b Graduate Student, School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark. c Senior Consultant, Department of Neurology and Clinical Neurophysiology (Dystonia Clinic), Bispebjerg Hospital, Copenhagen, Denmark. d Professor Emeritus, Department of Neurology and Clinical Neurophysiology (Dystonia Clinic), Bispebjerg Hospital, Copenhagen, Denmark. Received for publication Nov 12, 2011; returned for revision Apr 11, 2012; accepted for publication Apr 24, 2012. © 2013 Elsevier Inc. All rights reserved. 2212-4403/$ - see front matter http://dx.doi.org/10.1016/j.oooo.2012.04.023

of food bolus, swallowing, breathing, and both verbal and nonverbal communication. Electromyographic (EMG) recordings have shown deviating masticatory muscle activity, such as cocontractions of antagonists and loss of rhythmicity during chewing.7,14 Depending on the subtype, OMD may also be accompanied by trismus, bruxism, and forceful involuntary jaw closure or temporomandibular joint dislocation, which may lead to trauma and damage of the structures of the oral cavity, dental restorations, and dentures.2,15 Thus, jawclosing dystonia may result in excessive dental wear, dental fractures, and trauma of the lips, gums, and tongue, whereas jaw-opening dystonia may be associated with temporomandibular joint overload.12,16,17 The prevalence of OMD varies. It has been reported to be as high as 6.9 cases per 100,000 and the incidence up to 3.3 cases per 1,000,000.18 Women seem to be affected more frequently than men, and the onset is typically between the age of 45 and 70 years.19 OMD is usually idiopathic (primary), focal, or part of segmental dystonia; however, it may also be secondary to other movement or neurological disorders, injuries, infections, or induced by antipsychotic drugs (tardive).20 Because of its rare occurrence, patients with OMD are probably often misdiagnosed or their diagnosis may be delayed. Consequently, these patients may also receive incorrect dental treatment.16 In some cases, OMD has been associated with ill-fitting dentures, but a causal relationship is uncertain, as such problems may be both an effect and a cause for dystonia.2 Generally the pathophysiology of OMD is unclear. Dystonia is thought to be associated with dysfunction of the basal ganglia, and the excess movement in dystonia to be to

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Table I. Demographic characteristics of 21 patients (13 women and 8 men) with oromandibular dystonia (OMD) Characteristics Age, y Age at onset of symptoms, y Time since onset of symptoms, y F-M dystonia scale for mouth, 0-8 Subjective assessment of OMD severity, 100 mm VAS

Mean ⫾ SD; median (range) 56.7 ⫾ 12.7; 58 (27–78) 50.2 ⫾ 17.0; 52 (6–76) 6.4 ⫾ 7.7; 3 (1–24) 5.8 ⫾ 2.7; 6 (0–8) 72.2 ⫾ 24.3; 78 (17–100)

F-M dystonia scale, Fahn-Marsden rating scale assessed from video recordings30; VAS, visual analogue scale.

the result of a loss in inhibition of motor control.21 Neurophysiologic and neuroimaging studies have shown a number of motor and sensory abnormalities at cortical and subcortical levels, probably reflecting a dysfunction in the basal ganglia-thalamo-cortical circuits.22,23 M any patients with OMD experience symptom relief by the use of sensory tricks, also known as gestes antagonistes, where tactile stimulation modifies and alleviates the dystonic muscle activity.24,25 The maneuvers may consist of lightly touching the chin or the lips, singing/humming, yawning, chewing gum, or biting on a toothpick. In contrast, other patients experience an aggravation or triggering of the OMD symptoms by chewing and talking, whereas stress and depression may generally increase the dystonic activity.26 Intramuscular injection with botulinum toxin (BTX) is the therapy of choice for symptom relief in OMD.4,16 BTX is a potent neuromuscular paralyzing agent, blocking the release of acetylcholine at the presynaptic junction and thereby functionally denervating the muscle.27 It may be used either alone or in combination with peroral medication and its use in different OMD subtypes has been well documented.3,6,19,28,29 Knowledge of the clinical characteristics of OMD is important for early diagnosis and relevant treatment. Details of hampered orofacial function in patients with OMD have been reported, but no comprehensive report on OMD characteristics with special relevance for dentists has previously been published. The purpose of the present study was therefore to describe orofacial function in patients with OMD, and to describe results of special dental importance.

MATERIAL AND METHODS Patients The study included data from 21 consecutive patients (13 women and 8 men; age range 27-78 years [Table I]), who were diagnosed with OMD.28 The patients were referred from neurologists and dentists to the

Dystonia Clinic, Bispebjerg Hospital, Copenhagen, from February 2006 to October 2010. In general, there was a year-long delay from onset of symptoms until referral for thorough examination and treatment. The patients had no other neurological disorders except for one patient with migraine. Fourteen of the patients were already in treatment for their dystonia with antiepileptic (clonazepam), anti-Parkinson (benzhexol, biperidon), or neuroleptic (tetrabenazine) drugs; the rest had never been treated for their dystonic symptoms. A further 2 patients were treated with antidepressive drugs (amitryptyline and escitalopram). The description of the patients comprised the results from the standard examinations performed to classify OMD and plan BTX treatment. After their treatment was started, they were asked if we could use their data anonymously for publication. All patients provided their written informed consent. The investigation followed the guidelines of the Helsinki Declaration and was approved by the local scientific and ethical committee at the Bispebjerg Hospital. Clinical and video assessment of dystonia OMD of the mouth was scored objectively (Fahn-Marsden rating scales30) from standardized video recordings comprising sequences with the face at rest, reading, maximal biting, eating of apple, speaking, and voluntary opening, and protrusive and lateral movements of the jaw. The dominating OMD subtype was also assessed from the videos. In addition, the patients rated their OMD on a horizontal 100-mm visual analogue scale (VAS; the left end point indicated no symptoms and the right end point the worst imaginable symptoms). They were also asked if they had frequent headaches or facial pain (ⱖ1 time per week). EMG assessment of dystonic activity Data were acquired from the masticatory, lip, and tongue muscles and analyzed with a custom-designed 8-channel EMG system after amplification and filtering (gain 500-10,000; high-pass filter at 20-50 Hz and low pass at 1 kHz). The EMG signal was digitized with a sample frequency of 2.5 Hz and 12-bit resolution. The recordings of spontaneous activity during rest and masticatory activity were performed with reusable, bipolar surface electrodes (tin plates, 3.0 ⫻ 1.5 ⫻ 10.0 mm for anterior temporal and masseter muscles and 3.0 ⫻ 1.5 ⫻ 5.0 mm for anterior digastric and lip muscles, 10-mm distance between electrodes) covered with electrode paste. After cleaning the skin with alcohol to reduce impedance, the electrodes were placed transversely to the fiber direction. Recording of spontaneous activity during rest from the lateral pterygoid muscle (intraoral approach) and the genioglossus muscle (extraoral ap-

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proach) was performed with disposable concentric needle electrodes (50 ⫻ 0.46 mm, 26 G; Alpine Biomed, Skovlunde, Denmark). The spontaneous activity was assessed as dystonic if the mean amplitude from three 10-second recordings exceeded the upper level of the guiding reference interval (Electromyographic Laboratory, School of Dentistry, Faculty of Health Sciences, University of Copenhagen) and if the number of turns (potential reversals ⬎100 ␮V for needle electrodes and ⬎50 ␮V for surface electrodes) exceeded 100 in the activity bursts.31 Assessment of functional parameters Screening for orofacial dysfunction. The Nordic Orofacial Test (NOT-S32) was used to perform a comprehensive screening of orofacial dysfunction.33 It consisted of a structured interview and a clinical examination. The interview reflected 6 domains (sensory function, breathing, habits, chewing and swallowing, drooling, dryness of the mouth), and the examination included 6 domains (the face at rest, nose breathing, facial expression, masticatory muscle and jaw function, oral motor function, speech). One or more “yes” responses for impairment in one of the 12 domains scored 1 point, and the maximum score was 12 points. Masticatory ability. The Mastication Index modified after Yoshida et al. was used to assess the subjective chewing efficiency.33,34 The index had 5 answer possibilities: 0, Are you able to eat anything without problems; 1, Are you able to eat anything, but it takes long time; 2, Are you able to eat soft diet only; 3, Are you able to eat soft diet only, and it takes long time; or 4, Are you able to eat liquid diet only. The participants were asked to choose the answer that fit best with their perceived masticatory ability. Masticatory performance. The objective chewing efficiency was measured by the apple chewing time(s) assessed from the video recordings, that is, the duration of the chewing of a standardized slice of green, crisp apple (11 g Granny Smith with rind and core removed) from the first bite to the spontaneous termination swallow.33 Masticatory rhythm. The duration of the chewing cycle (milliseconds) during chewing of apple slices was assessed from the average of 5 strokes in 2 chewing sequences measured automatically by the EMG system with the right anterior temporal muscle as reference muscle (definition of chewing cycle: from the start temporal activity of one closing phase to the start of temporal activity in the next closing phase). Jaw-closing force. Bite force during maximum tooth clenching for 1 to 2 seconds was recorded with a strain-gauge transducer (Kleven, Oslo, Norway) placed unilaterally on the mandibular first molars. The trans-

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ducer was covered with protective plastic tubes and connected to an amplifier with peak storage facility.35 The molar bite force (N) was assessed as the average of the stored peak values from right and left side (2 at each side with intervals of about 0.5 min). Jaw-opening range. Maximum active jaw opening was measured in millimeters at the incisors, taking the (positive, neutral, or negative) vertical overlap between the maxillary and mandibular incisor teeth into account. Dental status. The complement of teeth and the presence of marked attrition in the frontal and premolar region (ⱖ3°; Broca’s classification of dental attrition 0-4°) were recorded by clinical inspection. In addition, the presence of caries and marginal periodontitis was also noted. Unstimulated salivary flow rate. The resting salivary secretion was assessed by the draining method with a collection time of 5 minutes.36 Immediately before collection, the patient was asked to perform one swallow and hereafter not to swallow during the saliva collection. The saliva was collected into a plastic cup and at the end of the collection period, the patient was asked to spit the remaining saliva volume in the mouth into the cup. Saliva flow rates were determined by weight, where 1 g equals 1 mL of saliva. Plastic cups were weighed before and reweighed after the saliva collection and the weight difference was calculated to determine the salivary flow rate. Statistical evaluation. The data were analyzed with conventional statistical methods (Statistica, version 5.0; StatSoft, Tulsa, OK) and were presented as mean, standard deviation, median, and range.

RESULTS Both patient-based and clinic-based evaluations of OMD assessed the patients’ condition as severe (Table I). In 13 patients the OMD was focal, in 7 it was segmental and associated with either blepharospasms (Meige’s disease) or torticollis, and in 1 patient it was multifocal and associated with writer’s cramp. None of the patients had a family history of dystonia. The OMD was classified as primary in 16 patients and as secondary in 5 patients. Three of the secondary cases were tardive induced after pharmacotherapy and 2 cases related to either injury or infection. In 7 patients (33%), orofacial function aggravated the dystonic activity. In one of these patients there was no dystonia at rest, but OMD was provoked by speaking and singing (Table II). Chewing, biting, speaking, or singing also aggravated the dystonia in another 6 of the 21 patients. In contrast, the same functions were used as sensory tricks for symptom relief as well, but not in the same patients. A total of 6 patients used such

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Table II. Types of oromandibular dystonia in 21 patients assessed from video recordings Dominating subtype “at rest”

n (%)

Mixed Jaw opening Munching Tremor Jaw closing Jaw deviating Only dystonia when speaking or singing

9 (43) 4 (19) 3 (14) 2 (9) 1 (5) 1 (5) 1 (5)

Table III. Involvement of masticatory, lip, and tongue muscles in 21 patients with oromandibular dystonia assessed by electromyography Muscles*

n (%)

Digastric, anterior belly Anterior temporal Lateral pterygoid Masseter Inferior orbicularis oris Superior orbicularis oris Genioglossus

13 (62) 10 (48) 10 (48) 8 (38) 6 (29) 2 (10) 9 (43)

*Each patient may have dystonic activity in more than one muscle.

sensory tricks, which also included finger pressure on the jaw. A mixture of 2 or more subtypes was the most common dominating form of OMD (43%); jaw-opening and munching dystonia were the most frequent single subtypes (19% and 14%, respectively; Table II), which corresponded well with the frequent involvement of anterior digastric, lateral pterygoid, and anterior temporal muscles (Table III). In each of the patients, 1 to 5 of the investigated masticatory, lip, or tongue muscles showed dystonic activity. The screening for orofacial dysfunction showed high prevalence of dysfunctions. The masticatory function was impaired in several ways, but the jaw-opening range was generally normal (Table IV). The unstimulated saliva flow rate varied, but was on an average low (0.25 ⫾ 0.21 mL/min).39 Besides hyposalivation, dysphagia and dental attrition were frequent in the patient group (38%-43%; Table V). No other local complaint or clinical finding was equally frequent, but reduced control of the jaw and dental, occlusal, and prosthetic problems were also present.

DISCUSSION Our sample of 21 patients was small, but OMD is very rare; however, the sample seemed to be fairly representative for this movement disorder because the general characteristics of the patient group, such as sex and age distributions and time of onset, were in agreement with descriptions in previous reports on OMD.1–14,24 –26 Also, the prevalence of jaw opening and jaw deviation was similar to the findings in the large number of patients with OMD published by Tan and Jankovic.19 However, half of their patients were classified as jawclosing dystonia, whereas this subtype constituted only a low percentage of the present patient group. This may be because we also had a group characterized as munching dystonia. Thus, the difference between the present data and the previous findings by Tan and Jankovic19 may actually be smaller, as munching was probably included into their subtype of jaw-closing dystonia.

As the result of the dystonic activity and often forceful contractions, associated muscle pain presenting as headache and facial pain might be expected; however, such pain was reported by only 5 (24%) of our patients. Instead, the remaining patients often described a feeling of muscular tension or tiredness. Masticatory muscle pain does not seem to play an important role in OMD, as pain was usually not reported in previous studies on OMD. Moreover, in the thorough review by Blanchet et al.,2 pain was mainly mentioned as oral pain in edentulous patients and present in only about 20% (i.e., probably related to structures other than the muscles). On average, there was a moderate impediment of oral function in the present study, especially of mastication and swallowing. Also, the electromyographic recordings showed deviating masticatory function, as in previous studies.7,14 However, the variation among patients was great, from almost no influence to marked influence from the OMD. A finding not previously reported, of potential clinical relevance, was the hyposalivation. The reduced salivary flow rate may be associated with the ongoing drug treatment. Together with the dystonia, hyposalivation may add to oral dysfunction in terms of dysphagia and mastication. It may also increase the caries risk.40 The marked dental attrition was probably associated with the dystonic activities, the tooth loss, and by the hyposalivation, because of less lubrication. The OMD may also have caused or aggravated some of the other dental and prosthetic problems. Thus, when planning dental treatment and prosthetic reconstructions, the subtype of OMD and the possible dystonic movements and forces should be considered. In conclusion, patients with OMD may present to dentists with involuntary jaw movements, inability to bite repeatedly in an intercuspal position, and functional problems. Prosthetic treatment in these patients may be difficult with risk of incorrect occlusion and denture retention problems. Patients with OMD may also need control and treatment of hyposalivation as well as prevention of attrition and damage to restora-

29.0 ⫾ 1.5§ 24.3 ⫾ 7.3¶

Table V. Local complaints and oral findings in 21 patients with oromandibular dystonia

54.9 ⫾ 4.5§ 52.5 ⫾ 4.4§

Symptoms and signs*

n (%)

Dysphagia Hyposalivation Marked dental attrition Reduced control with voluntary jaw movements or uncertain intercuspal position Weekly headache or facial pain Full and/or partial dentures Lack of molar support Caries lesions and fractured fillings Denture adaptation problems, alveolar atrophy and granulomatous tissue reaction General marginal periodontitis

9 (43) 9 (43) 8 (38) 6 (29) 5 (24) 3 (14) 3 (14) 2 (10) 2 (10) 1 (5)

*The patient may have more than one complaint or finding.

NOT-S, Nordic Orofacial Test. *Bakke et al. 2007, 3-78 y.32 † Guiding reference interval (Electromyographic laboratory, School of Dentistry, Faculty of Health Sciences, University of Copenhagen). ‡ Goshima et al. 2010, 21-30 y.37 § Bakke et al. 1990, 21-30 y and 61 to 70 y.38 ¶ Bakke et al. 2011, 61-82 y.33

572.3 ⫾ 72.2 § 373.8 ⫾ 138.2§ 441–785†

946.2 415.3 768 509 2175 77.5 61.0 60 20 268

Mean 4.2 1.1 SD 1.8 1.0 Median 5 1 Minimum 0 0 Maximum 7 3 Reference values (mean ⫾ SD or guiding interval) All age groups 0.4 ⫾ 0.7* Young 0 ⫾ 0‡ Old 0 ⫾ 0¶

17.9 ⫾ 6.2‡ 34.4 ⫾ 4.2¶

23.8 7.1 27 3 30 52.6 7.5 51 39 66

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296.7 219.8 267 27 800

Natural teeth, no. Jaw movement: Opening capacity, mm Jaw-closing force: Molar bite force, N Masticatory rhythm: Apple chewing cycle, ms Masticatory performance: Apple chewing time, s Masticatory ability: Mastication index, 0-4 Orofacial dysfunction NOT-S, 0-12

Table IV. Screening of orofacial dysfunction, and functional parameters of chewing, bite force, and maximal jaw opening capacity in 21 patients (27-78 year) with oromandibular dystonia

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Reprint requests: Merete Bakke, DDS, PhD, dr.odont. Department of Oral Medicine (Clinical Oral Physiology) School of Dentistry, Faculty of Health Sciences University of Copenhagen 20 Nørre Allé Copenhagen N, DK-2200, Denmark [email protected]